Analysis of Shear Characteristics of Recycled Concrete Aggregate–Geogrid Interface

Abstract

Recycled concrete aggregate (RCA) has been widely used as a resource in reinforced soil structures, especially as a substitute for natural aggregate. Direct shear tests were conducted using a dynamic direct shear apparatus to study the effects of particle-size gradation (0.06–37.5 mm) on the shear properties of RCA-geogrid interface, in which geogrid was used to enhance the shear strength of RCA. The results exhibited that the geogrid significantly improved the interface peak strength of the RCA-geogrid interface. The inclusion of geogrid reduced the vertical displacement of RCA. The shear strength of the RCA-geogrid interface with different gradations increased with an increase in the relative density (RD) in the monotonic direct shear test. In the cyclic direct shear tests, the shear stiffness of the well-graded RCA(R2)-geogrid interface was the largest and the damping ratio of the discontinuous-graded RCA(R3)-geogrid interface was the smallest. In post-cyclic monotonic direct shear, the RCA-geogrid interface shear strength increased significantly, from 26.5% to 48.3%. After the cyclic shearing, the interface apparent adhesion and friction angle increased and the R2-geogrid interface demonstrated superior shear properties.